Non-Hodgkin's lymphoma originating from mucosa-associated lymphoid tissue has been connected with autoimmune disease. These tumours often arise in gastric mucosa and are extremely rare in airway mucosa. Three cases of mucosa-associated lymphoid tissue lymphoma in the cavum have been reported in the literature. A 52-year-old male with rheumatoid arthritis presented with an 8-month history of nasal obstruction and recurrent nasal blood discharge. On physical examination a bulky mass was observed in the nasopharynx. CT demonstrated a soft tissue lesion in the nasopharynx without bone destruction. MRI showed a contrast-enhanced mass with extension to the left pterygoid muscle. Biopsy revealed a low-grade B-cell lymphoid tumour of the marginal zone. The patient received six cycles of cyclophosphamide, vincristine and prednisone with adriamycin treatment, together with intracranial methrotrexate as a prophylactic measure. After 48 months of follow-up there was no evidence of disease and a control MRI scan was normal. The prognosis of this type of tumour is unpredictable and there are too few cases to enable definitive conclusions to be drawn.